Attachment for the microanalysis of blood gases

ABSTRACT

An attachment for the cleaning and drying of measuring capillary tubes for the microanalysis of blood gases having a measuring vessel containing the capillary tube to receive a blood test sample and a measuring electrode arrangement in contact with the test sample and having a scavenging duct connectable to one end of the tube.

tates merit 1 llnite [151 3,639,830

Harnoncourt Feb. 1, 1972 [54] ATTACHMENT FQR THE [56] References CitedMl R NA YSIS F BL D SES C 0A L 0 00 GA UNITED STATES PATENTS [72]Invent: Karl Hammwm Ausma 3,282,651 1 1/1966 Ferrari ..23/253 [73]Assignee: Hans List, Graz, Austria 3,327,204 6/1967 Hillier ..324/30Filed: p 23 1969 3,398,079 8/l968 Arthur ..324/30 X [21] Appl. No.;818,560 Primary Examiner-Michael J. Lynch Attorney-Watson, Cole, Grindle& Watson [30] Foreign Application Priority Data [57] ABSTRACT Apr. 30,1968 Austria ..A 4209/68 An attachment for the cleaning and drying ofmeasuring capil lary tubes for the microanalysis of blood gases having amea- [52] US. Cl. ..324/30 R, 23/253, 23/230 B, Suring vessel containingthe capillary tube to receive a blood 204/1 T test sample and ameasuring electrode arrangement in contact [51] Int. Cl. ..G0ll1 27/42with the test Sample and having a scavenging duct connectablc [58] Fieldof Search ..324/30, 29; 204/1 l, 195; to one end f the tube.

4 Claims, 2 Drawing Figures slssslaao mm mm In via nib;- KzrZHarwovzcoart By ATTACHMENT FOR THE MICROANALYSIS OF BLOOD GASES Theinvention relates to an attachment for the cleaning and drying ofmeasuring capillary tubes of a measuring device for the microanalysis ofblood gases, comprising at least one measuring vessel containing themeasuring capillary tube receiving the blood test sample and a measuringelectrode arrangement in contact with the blood test sample and ascavenging duct connectable to one end of the measuring capillary tubeand supplied with a cleansing liquid, such as distilled water, from acontainer, and a suction pump connectable to the other end of themeasuring capillary tube.

Microanalysis of the blood gases includes the determination of variousvalues of importance for the diagnosis of ailments of the heart, lungs,or of metabolic diseases, such as the pH value and the partial oxygenand/or carbon dioxide pressures of a blood test sample. The advantageoffered by the microanalysis of blood gases as compared with formermethods of examination resides in the fact that a few drops of bloodonly are required to carry out all sorts of measurements. However, theseadvantages are partly offset by the fact that owing to the small bloodvolume the instruments required for the various measurements have to beequipped with measuring capillary tubes which are extremely difficult tocleanse. This cleansing procedure comprises the scavenging of themeasuring capillary tubes, for example with distilled water andsubsequent drying. The measuring capillary tubes have to be cleansed notonly prior to every measurement, but also before and after eachcalibration of the measuring electrodes which becomes necessary atcertain intervals of time as well as in connection with variousintermediate operations.

A conventional measuring instrument for the microanalysis of blood gasescomprises preferably cup-shaped measuring vessels closed on all sidesand thermostatized at about 37 C. by a liquid charge. Into measuringvessel preferably U-shaped measuring capillary tubes are sealed whoseupright arms terminate in flared-out receiving apertures which are openin the direction of the upper side of the measuring vessel. Theelectrode arrangement is connected to the horizontal portion of themeasuring capillary tube. In one arm of the measuring capillary tubeterminates, on one side, the gas feed pipe which serves to carry acalibration gas or an equilibration gas, depending on the nature of themeasuring operation, to the capillary tube. Into the opposite receivingbore of the measuring capillary tube a pipe elbow can be inserted, thefree end of which serves as a hose liner. This is the place forconnecting various attachments of the instrument depending on theoperations to be performed. For the cleaning of the measuring capillarytube provision should be made for a hose line connecting the hose linerto a suction pump. At the same time, distilled water has to beintroduced in any suitable manner (for example, from a wash-bottle) intothe opposite receiving aperture of the measuring capillary tube. Thesuction action of the pump thus produces a vacuum in the measuringcapillary tube, as a result of which the blood test sample is drawn offand distilled water is forced through the measuring capillary tube. Forthe drying of the measuring capillary tube the receiving apertureopposite the suction stub is cleared and air is drawn through thecapillary tube. For the next operation the suction pump should again bedisconnected.

With this conventional apparatus, the cleaning and drying of themeasuring capillary tube is not only complicated and tiresome, butgenerally also incomplete, since it frequently happens that a drop ofwater penetrates into the aperture of the gas feed pipe, as a result ofwhich the subsequent electrode calibration or a subsequente'quilibrating operation is disturbed and will cause measuring faults ifnot detected in due course. These shortcomings of conventional devicesare responsible for uncontrollable falsifications of the results of themeasurements. Moreover, proper operation of the device requires thoroughtraining and considerable experience on the part of the operator if sucherrors are to be avoided.

It is the object of the present invention to improve upon and simplifythe cleaning and drying process in connection with a measuringinstrument for the analysis of blood gases with a view to speeding upoperations and producing test readings of greater precision. Accordingto the invention, the attachment required for this purpose features aswitchover device connected to the suction pump and comprising at leastone scavenging pipe mounted on the mobile switch member andcommunicating with the scavenging duct, the open end of the connectingpipe being tightly connected to one end of the measuring capillary tubein one final switch position (scavenging position) of the switchoverdevice where the other end of the measuring capillary tube communicateswith the suction pump via the switch member, whereas in an intermediateposition (drying position) of the switchover device the scavenging pipeis separated from the measuring capillary tube and in the second finalswitch position (position of rest), communication between the measuringcapillary tube and the suction pump is interrupted.

Thus the entire cleansing and drying process is completely automatic andthe positive cleansing and complete drying of the measuring capillarytube at any stage of operations merely requires'a flick of theswitchover device. Consequently, the operator is allowed to proceedforthwith with the next measuring operation.

Since'visual control of the state of cleanliness of the measuringcapillary tube is not required and all operations are greatly simplifiedas hereabove explained the instrument can be entrusted to the care ofany unskilled operator.

Basically, there are two different possibilities of connecting themeasuring capillary tube via the switchover device to the suction pump,the simplest method consisting in providing at the appropriate end ofthe measuring capillary tube a switch cock establishing communicationwith calibration gas connections or with an intermediate line leading toa switchover device, as required.

On the other hand, a preferred method of connecting the suction pump tothe measuring capillary tube according to the invention consists in theprovision of a mobile suction pipe connected to the switch member, thefree end of the said suction pipe being tightly connected, both in thescavenging position and in the drying position of the switchover device,to the end of the measuring capillary tube opposite the scavenging pipeon the one hand, and via the switch member to the suction pump on theother hand, whereas in the position of rest of the switchover device thesaid suction pipe is both separated from the measuring capillary tubeand disconnected from the suction-pump. This embodiment of the inventionis particularly advantageous since it permits absolute functionalseparation of the cleaning and drying apparatus from the measuringsystem proper. Space saved owing to the absence of an intermediate lineleading to the switchover device is now available for the convenientaccommodation of calibration gas and other connections required for themeasuring system.

According to a further embodiment of the invention, simplicity of designand dependability in operation are particularly increased by the use ofa rotary slide valve as a switchover device, the switch member of thesaid rotary slide valve presenting an arched recess through which twocontrol bores provided on the stationary member of the switchoverdevice, one of which communicates with the suction pump and the otherwith the measuring capillary tube and/or the suction pipe, areinterconnected both in the scavenging position and in the dryingposition of the switchover device. The scavenging pipe and the suctionpipe, if any, can be designed in a simple manner as swiveling armsconnected with the switch body, the said swiveling arms being completelyswung clear of the measuring system if necessary, so as to facilitateoperations.

Further details of the invention will appear from the followingdescription of two embodiments of the invention with reference to theaccompanying schematic drawing in which:

FIG. 1 is a longitudinal section of a measuring vessel equipped with acleansing and drying device according to the invention,

FIG. 2 is a sectional view of a preferred embodiment of the inventionsimilar to FIG. 1.

In both embodiments of the invention the measuring vessel is designed asa hollow glass cylinder 1 closed at both ends by means of caps 2 andfilled with a liquid maintained at body temperature by means of athermostat. The hollow glass cylinder 1 contains a measuring capillarytube 3, both ends of which communicate with conical receiving bores 4leading to the upper side of the cylinder 1. Between the two receivingbores 4 two additional receiving hoppers 5 for each of the measuringelectrodes 26. The connecting pipes of the measuring electrodes 26 aredesignated by reference numeral 27.

In one receiving bore 4 of the instrument shown in FIG. 1 a switchcock 6with control knob 7 is located, by means of which the measuringcapillary tube 3 can be connected to a connecting pipe 8 branching offthe left receiving bore 4 or else to a calibration gas or other pipe(not shown) associated with the measuring system, as required.

In spaced relation to the hollow glass cylinder 1 a switchover device 9designed as a rotary slide valve is arranged, the rotatable or mobileswitch member 10 of which presents a curved recess or control groove 11cooperating with two control bores 12 and 13 provided on the stationarybase 10 of the switchover device 9. One of the two control bores 12communicates with the connecting pipe 8 leading to the measuring vessel.The other control bore 13 communicates with a suction pump 25 via aconnecting pipe 14 and a waste water container 24 included in thesuction pipe.

Attached to the switch member 10 is a scavenging pipe 15 in permanentcommunication with a scavenging duct 16 through which distilled waterfrom a reservoir 23 can be drawn in. The scavenging pipe 15 which restswith the interposition ofa pressure spring 17 on a rigid stop 18 and canbe swung to the required position together with the switch member 10 ofthe switchover device 9 by means of a control knob 19, presents adownwardly bent end 20 with a circumferential joint 21 on top. This pipeend 20 can be inserted in the free receiving bore 4 of the measuringvessel by depressing the knob 19. The circumferential joint 21 thentightly adjoins the conical inner wall of the aperture 4, as indicatedby dotand-dash lines in FIG. 2. As a result of the action of thepressure spring 17 the scavenging pipe 15 and consequently, the switchmember 10 occupies the position indicated by solid lines. When theswitchover device 9 is' in its position of rest, the scavenging pipe 15is swung up (also indicated by dashand-dot lines in the drawing).

For cleaning the measuring capillary tube 3, the switchcock 6 is firstplaced in the position shown, where the capillary tube 3 communicateswith the connecting pipe 8. The scavenging pipe 15 is now moveddownwards from its position of rest and placed in its bottommost endposition (scavenging position) against the action of the pressure spring17. In this position of the switch member 10 the two control bores 12and 13 of the switchover device 9 communicate via the recess 11 of theswitch member 10 and consequently, the lines 8 and 14 are alsointerconnected. As a result, the suction pipe draws the blood containedin the measuring capillary tube 3 off through the connecting pipe 8, theswitchover device and the suction line 14. By means of the vacuumproduced in the measuring capillary tube 3, distilled water is drawnfrom the reservoir 23 via the scavenging line 16 through the scavengingpipe 15 and passed through the capillary tube. As soon as the measuringcapillary tube 3 has been cleared of any residual blood, the knob 19 ofthe switchover device is released and the spring 17 raises theconnecting pipe 15 into the intermediate position (drying position)indicated by solid lines, thereby clearing the receiving bore 4. Sincein this intermediate position communication between the suction pump andthe capillary tube 3 is maintained, air is drawn into the capillary tubethrough the exposed receiving bore 4. Once the capillary tube has dried,the switchover device is again moved into its position of rest.

The instrument as shown in FIG. 2 differs from the embodiment of theinvention illustrated in FIG. 1 only by the manner of connecting thesuction pump to the measuring capillary tube 3. In fact, the connectingline 8 leading to the suction pump 25 has been replaced by a suctionpipe 22 similar to the scavenging pipe 15, also carrying acircumferential joint 21 at its free end and tightly insertable into thesuction-end receiving bore 4 of the measuring capillary tube 3. Thesuction pipe 22 communicates either directly or via the switchoverdevice 9 with the suction pump.

For the cleansing of the measuring capillary tube 3, first the suctionpipe 22 and, immediately after, the scavenging pipe 15 is introducedinto the corresponding receiving bore. Via the suction pipe 22 blood isremoved by suction from the capillary tube 3, as is the distilled waterflowing in its wake through the scavenging pipe 15. The scavenging pipe15 is then placed in the intermediate position illustrated in FIG. 3 andair is drawn through the capillary tube 3 via the free receiving bore 4.

I claim:

1. A measuring instrument for the microanalysis of blood gasescomprising a measuring vessel having a measuring capillary tube capableof receiving a blood test sample mounted therein, said vessel having aplurality of receiving bores extending in transverse relation to saidmeasuring capillary tube and terminating in said measuring capillarytube, a plurality of measuring electrodes, each of said electrodeslocated in one of said receiving bores respectively and in contact withsaid blood test sample in said measuring capillary tube, a device forcleansing and drying said measuring capillary tube comprising areservoir containing a cleansing liquid, a suction pump, a switchoverdevice consisting of a stationary base having two control bores and amanually moveable switch member mounted on the base and moveable from afinal rest position via an intermediate position into a final scavengingposition, a control groove on said switch member interconnecting saidcontrol bores in the intermediate and final scavenging positions of saidswitch member, a scavenging pipe attached to and moveable with saidswitch member, a scavenging line connecting one end of said scavengingpipe with said reservoir, the other end of said scavenging pipe beingdirectly connected with one end of said measuring capillary tube in thesaid final scavenging position and separated from said measuringcapillary tube in the remaining positions of said switch member, asuction pipe having two sections, the first section connecting the otherend of said measuring capillary tube to one of said control bores, andthe second section connecting the second control bore with said suctionpump.

2. A measuring instrument according to claim 1 wherein said suction pipeis movable and is connected with said switch member of said switchoverdevice, said first section of said suction pipe being connected to thesaid suction pump through both said control groove and said secondsection of said suction pipe in the final scavenging position and in thedrying position of said switch member, said first section of saidsuction pipe being tightly connected with said measuring capillary tubeopposite said scavenging pipe in the final scavenging position and thedrying position but disconnected from said measuring capillary tube byreason of said control groove in the final rest position of saidswitchover device.

3. A measuring instrument according to claim 1, wherein the saidswitchover device is designed as a rotary slide valve having astationary base comprising the aforesaid two control bores and a switchmember rotatably mounted on said base, said switch member having acurved recess forming said control groove, said recess covering said twocontrol bores and interconnecting the aforesaid two sections of saidsuction pipe in the final scavenging position and in the drying positionof said switchover device.

4. A measuring instrument according to claim 2, wherein said switchoverdevice is designed as a rotary slide valve having a stationary base withtwo control bores and a switch member rotatably mounted on said base,and having a curved recess forming said control groove, said recesscovering the two control bores and connecting said suction pipe via saidsecond section of said suction pipe with said suction pump in the finalscavenging position and in the drying position of said switchoverdevice.

1. A measuring instrument for the microanalysis of blood gasescomprising a measuring vessel having a measuring capillary tube capableof receiving a blood test sample mounted therein, said vessel having aplurality of receiving bores extending in transverse relation to saidmeasuring capillary tube and terminating in said measuring capillarytube, a plurality of measuring electrodes, each of said electrodeslocated in one of said receiving bores respectively and in contact withsaid blood test sample in said measuring capillary tube, a device forcleansing and drying said measuring capillary tube comprising areservoir containing a cleansing liquid, a suction pump, a switchoverdevice consisting of a stationary base having two control bores and amanually moveable switch member mounted on the base and moveable from afinal rest position via an intermediate position into a final scavengingposition, a control groove on said switch member interconnecting saidcontrol bores in the intermediate and final scavenging positions of saidswitch member, a scavenging pipe attached to and moveable with saidswitch member, a scavenging line connecting one end of said scavengingpipe with said reservoir, the other end of said scavenging pipe beingdirectly connected with one end of said measuring capillary tube in thesaid final scavenging position and separated from said measuringcapillary tube in the remaining positions of said switch member, asuction pipe having two sections, the first section connecting the otherend of said measuring capillary tube to one of said control bores, andthe second section connecting the second control bore with said suctionpump.
 2. A measuring instrument according to claim 1 wherein saidsuction pipe is movable and is connected with said switch member of saidswitchover device, said first section of said suction pipe beingconnected to the said suction pump through both said control groove andsaid second section of said suction pipe in the final scavengingposition and in the drying position of said switch member, said firstsection of said suction pipe being tightly connected with said measuringcapillary tube opposite said scavenging pipe in the final scavengingposition and the drying position but disconnected from said measuringcapillary tube by reason of said control groove in the final restposition of said switchover device.
 3. A measuring instrument accordingto claim 1, wherein the said switchover device is designed as a rotaryslide valve having a stationary base comprising the aforesaid twocontrol bores and a switch member rotatably mounted on said base, saidswitch member having a curved recess forming said control groove, saidrecess covering said two control bores and interconnecting the aforesaidtwo sections of said suction pipe in the final scavenging position andin the drying position of said switchover device.
 4. A measuringinstrument according to claim 2, wherein said switchover device isdesigned as a rotary slide valve having a stationary base with twocontrol bores and a switch member rotatably mounted on said base, andhaving a curved recess forming said control groove, said recess coveringthe two control bores and connecting said suction pipe via said secondsection of said suction pipe with said suction pump in the finalscavenging position and in the drying position of said switchoverdevice.